Fluidizing powdered or finely divided solids into a vapor stream is frequently required for adequate mixing and transport in various mechanical and chemical systems.
For example it is known to move sand, catalyst particles, comminuted coal, shale or the like from a chamber or cylinder by a piston acting directly against the particulate matter to entrain a portion of the bed into a fluid stream flowing over, or through a portion of the top of the mechanically raised bed of particles. In U.S. Pat. No. 1,578,944--Wilkinson and U.S. Pat. No. 2,708,140--Reed, the particle bed is mechanically raised by a piston moving upwardly in a chamber to force the particles at the top of the bed into contact with a flowing stream. In the latter patent, fluidization is aided by fluid flow upwardly through the lifted bed. U.S. Pat. No. 2,077,898 discloses a system in which the bed of particles moves downwardly by gravity and is assisted by a piston moving downwardly in the chamber. Fluid flows between the cylinder wall and the piston to entrain particles flowing out of the bottom of the chamber.
It is also known, as in U.S. Pat. No. 3,179,378--Zenz et al, to mix and transport finely divided solids by entraining the solid particles fed by gravity from an overhead shell or bin into a conduit inlet by an upwardly flowing gas stream. The inlet to the conduit may be moved up or down to control the rate particles are released from the overhead bin. Also gas pressure is applied to the upper end of the shell to force particles down into a conical section forming feed means into the gas stream.
U.S. Pat. No. 3,412,898--Marynowski discloses an arrangement for feeding a powdered material into a conduit from a chamber in which gas flows up through a bed of the material. Material is continuously or periodically added to the top of the bed to replace the entrained material. The fluidized particles-in-gas stream passes into an overhead conduit having an inlet at a fixed elevation in the chamber. A portion of the fluid flow is withdrawn through a permeable partition surrounding the conduit to control the leanness of the suspension in the fluid stream.
U.S. Pat. No. 2,789,015--Ward et al discloses a system for incorporating a powder material into an air stream by passing the air up through a bed of starch or the like in the bottom of a chamber. A fluidized powder pick-up, includes a conduit formed by an accordian hose surrounded by a pick-up cone which rests without restraint on the surface of the powder bed. The cone drops with the falling surface of the powder as it is entrained in air.